Adding live steam as stripping steam to a distillation column typically makes distillation operations possible at lower temperatures than without the added steam. Live steam can also be added when the distillation column is an extractive distillation column. Typically, the live steam is injected directly in the column shell below the last collector tray.
Incorporation of a reboiler into a distillation apparatus for use as a heating medium has numerous operational advantages, among which are making a distillation even possible. Although the use of reboilers is known in the art of distillation, the simultaneous use of a reboiler as both a heating medium for a distillation column and as a means for adding stripping steam in an extractive distillation process has not heretofore been described.
In view of the foregoing, improved methods and apparatuses for extractive distillation using a reboiler for both heating and for injection of stripping steam would have significant potential benefits in the art. Furthermore, reboilers having a modified design that allows for improved mass and heat transfer efficiency would also deliver significant benefits in the extractive distillation apparatuses and methods described herein.